Description: LY3020371 HCl is a novel, potent, selective mGlu2/3 (metabotropic glutamate 2/3) receptor antagonist with Ki of 5.3 and 2.5 nM, potently blocks cAMP formation with IC50 of 16.2 nM. LY3020371 hydrochloride exerts an antidepressant-like signature in vivo. The novel mGlu2/3 receptor antagonist, LY3020371, has been shown to produce antidepressant-like effects comparable to that of the clinically-effective antidepressant ketamine. In preclinical toxicology studies of 14day dosing of doses up to 1000mg/kg, i.v. in rats and up to 500m/kg, i.v. in Cynomologous monkeys, LY3020371 produced uM plasma exposures without producing critical toxicological findings. It is concluded that LY3020371 does not recapitulate the motor, cognitive, subjective, neurochemical, electrophysiological, or toxicological findings reported with ketamine. Thus, LY3020371 possesses both the efficacy signatures of a rapidly-acting antidepressant and a safety profile enabling proof of concept studies in patients.